JP6949568B2 - Explosion-proof panel and its manufacturing method - Google Patents

Description

The present invention relates to an explosion-proof panel and a method for manufacturing the same.

In an explosion accident caused by explosives or gas, when a flying object generated by the explosion collides with a concrete structure (concrete member), the structure is totally destroyed such as bending fracture or shear fracture, or surface fracture. , Backside peeling, penetration, etc. may occur locally. At this time, the concrete structure is also exposed to a high temperature due to an explosion. If the concrete structure is totally destroyed or locally destroyed such as penetration, the people, equipment, articles, etc. existing inside the structure will be damaged. Therefore, in order to protect people, equipment, and the like from flying objects and high temperatures generated by the explosion, a specific concrete structure at risk of being exposed to the explosion is required to have excellent impact resistance and fire resistance.

As a concrete structure having excellent impact resistance, for example, Patent Document 1 describes a cured product of a formulation containing at least cement, pozzolanic fine powder, aggregate particles having a particle size of 2 mm or less, water, and a water reducing agent. A sheet pile characterized by being composed of is described.

Japanese Unexamined Patent Publication No. 2001-207442

The compressive strength of the cured product of the formulation in the examples described in Patent Document 1 described above is 210 to 230 MPa. In this respect, if it is possible to produce a hardened cementum having a higher compressive strength, the thickness of the member made of the hardened body can be reduced, and the weight can be reduced. Further, the above-mentioned Patent Document 1 does not describe the fire resistance of concrete.
An object of the present invention is to provide an explosion-proof panel which is made of a hardened cementum having high compressive strength (for example, 270 N / mm ^{2 or more) and has excellent impact resistance and fire resistance.}

As a result of diligent studies to solve the above problems, the present inventor has found cement, ^{silica fume having a BET specific surface area of 15 to 25 m 2} / g, an inorganic powder having a 50% volume cumulative particle size of 0.8 to 5 μm, and maximum grains. Cement, silica fume and inorganic in 100% by volume of total amount of cement, silica fume and inorganic powder containing aggregate A having a diameter of 1.2 mm or less, a high-performance water reducing agent, a defoaming agent, metal fiber, organic fiber and water. The present invention has been completed by finding that the above object can be achieved by using a cured product of a cement composition in which each ratio of powder is within a specific numerical range as an explosion-proof panel.

That is, the present invention provides the following [1] to [8].
[1] An explosion-proof panel made of a hardened cement material, wherein the hardened cement material is cement, ^{silica fume having a BET specific surface area of 15 to 25 m 2} / g, and a 50% volume cumulative particle size of 0.8 to 5 μm. Inorganic powder, aggregate A having a maximum particle size of 1.2 mm or less, high-performance water reducing agent, antifoaming agent, metal fiber, organic fiber and water, and the total amount of the cement, silica fume and inorganic powder 100 It is a cured product of a cement composition in which the proportion of the cement is 55 to 65% by volume, the proportion of silica fume is 5 to 25% by volume, and the proportion of the inorganic powder is 15 to 35% by volume in% by volume. Explosion-proof panel.
[2] The above-mentioned cement includes coarse particles having a particle size of 20 μm or more, which is formed by polishing particles constituting moderate-heated Portoland cement or low-heated Portoland cement, and deforming an angular surface portion into a rounded shape. [1], which contains fine particles having a particle size of less than 20 μm produced by the polishing treatment, has a 50% volume cumulative particle size of 10 to 18 μm, and has a brain specific surface area of 2,100 to 2,900 cm ^{2 / g.} Explosion-proof panel described in.
[3] The organic fiber is a polypropylene fiber having a diameter of 0.010 to 0.020 mm, a length of 4 to 8 mm, and an aspect ratio (fiber length / fiber diameter) of 300 to 470. ] The explosion-proof panel described in.
[4] The explosion-proof panel according to any one of [1] to [3] above, wherein the hardened cementum has a compressive strength of 300 N / mm ^{2 or more.}
[5] The explosion-proof panel according to any one of [1] to [3] above, wherein the cement composition contains an aggregate B having a maximum particle size of more than 1.2 mm and 13 mm or less.
[6] The explosion-proof panel according to the above [5], wherein the hardened cementum has a compressive strength of 270 N / mm ^{2 or more.}

[7] The method for producing the explosion-proof panel according to any one of [1] to [6] above, wherein the cement composition is cast into a mold to obtain an uncured molded product. A molding step of obtaining the uncured molded body, and a room temperature curing step of obtaining a cured molded body by sealing or aerating the uncured molded product at 10 to 40 ° C. for 24 hours or more and then removing the mold from the mold. The cured molded product is cured by steam curing or hot water curing at 70 ° C. or higher and lower than 100 ° C. for 6 hours or longer, or autoclave curing at 100 to 200 ° C. for 1 hour or longer, and then curing after heat curing. A high-temperature heating step of obtaining a body and a high-temperature heating step of heating the cured product after the heat-curing at 150 to 200 ° C. for 24 hours or more (excluding heating by autoclave curing) to obtain the explosion-proof panel. A method of manufacturing an explosion-proof panel, which comprises.
[8] The method for producing an explosion-proof panel according to the above [7], which includes a water absorption step of causing the cured molded product to absorb water between the normal temperature curing step and the heat curing step.

Since the explosion-proof panel of the present invention is made of a ^{hardened cementum having high compressive strength (for example, 270 N / mm 2} or more) and excellent impact resistance, the thickness of the panel is reduced to reduce the weight. Can be planned. As a result, it is possible to significantly reduce the work load in carrying the panel to the construction site and assembling and installing the explosion-proof wall and the storage of explosives and the like using the panel.
Further, since the explosion-proof panel of the present invention is excellent in fire resistance in addition to the above-mentioned impact resistance, in the explosion-proof wall and the storage of explosives and the like constructed by using the panel, flying objects and high temperature generated by the explosion It is possible to protect people and equipment from.

It is a perspective view which shows an example of the explosion-proof panel of this invention. A view showing a flat plate specimen for an impact resistance test using a steel weight ((a): front view of the flat plate specimen, (b): side view of the flat plate specimen; the unit of numerical value is mm). Is. It is a front view of an example of a high-speed airflow agitator which partially includes a cross section cut in a direction perpendicular to the rotation axis of the rotor.

The explosion-proof panel of the present invention is made of a hardened cement material, which is cement, ^{a silica fumes having a BET specific surface area of 15 to 25 m 2} / g, and a 50% volume cumulative particle size of 0. An inorganic powder of 8 to 5 μm, an aggregate A having a maximum particle size of 1.2 mm or less, a high-performance water reducing agent, a defoaming agent, a metal fiber, an organic fiber and water, and of the cement, the silica fume and the inorganic powder. A cured product of a cement composition in which the proportion of the cement is 55 to 65% by volume, the proportion of the silica fumes is 5 to 25% by volume, and the proportion of the inorganic powder is 15 to 35% by volume in a total amount of 100% by volume. ..
In the present specification, "explosion-proof" means an application for stopping the damage of an explosion.
Hereinafter, the cement composition used in the present invention will be described in detail.

The type of cement is not particularly limited, and for example, various Portland cements such as ordinary Portland cement, early-strength Portland cement, ultra-early-strength Portland cement, moderate heat Portland cement, sulfate-resistant Portland cement, and low heat Portland cement, etc. Can be used.
Above all, from the viewpoint of improving the fluidity of the cement composition, it is preferable to use moderate heat Portland cement or low heat Portland cement.

Further, from the viewpoint of improving the fluidity of the cement composition and increasing the compressive strength of the hardened cement material, the cement is made by polishing particles constituting moderate heat Portland cement or low heat Portland cement, and is angular. It contains coarse particles with a particle size of 20 μm or more formed by deforming the surface portion into a rounded shape, and fine particles with a particle size of less than 20 μm produced by the above-mentioned polishing treatment, and has a 50% volume cumulative particle size of 10 to 18 μm. It is more preferable to use cement having a brain specific surface area of 2,100 to 2,900 cm ² / g (hereinafter, also referred to as “polished cement product”).

The upper limit of the particle size of the coarse particles is not particularly limited, but is usually 200 μm or less in consideration of the general particle size of the cement to be polished, and increases the compressive strength of the hardened cementum. From the viewpoint, it is preferably 100 μm or less.
The lower limit of the particle size of the fine particles is not particularly limited, but is preferably 0.1 μm from the viewpoint of improving the fluidity of the cement composition and improving the workability when producing a hardened cementum. Above, more preferably 0.5 μm or more.

For the polished cement, the 50% volume cumulative particle size is preferably 10-18 μm, more preferably 12-16 μm, and the brain specific surface area is preferably 2,100-2,900 cm ² / g, more preferably. Is 2,200 to 2,700 cm ² / g.
When the 50% volume cumulative particle size is 10 μm or more, the fluidity of the cement composition is improved. When the 50% volume cumulative particle size is 18 μm or less, the compressive strength of the cementum cured product becomes higher.
When the specific surface area of the brain is 2,100 cm ² / g or more, the compressive strength of the hardened cementum is higher. When the specific surface area of the brain is 2,900 cm ² / g or less, the fluidity of the cement composition is improved.

For the polishing treatment, a known polishing apparatus capable of polishing the particles constituting the cement (moderate heat Portland cement or low heat Portland cement) may be used. Examples of the polishing treatment apparatus include a commercially available high-speed airflow agitator (for example, manufactured by Nara Machinery Co., Ltd., trade name "Hybridizer NHS-3 type") and the like.
Hereinafter, the high-speed airflow agitator will be described in detail with reference to FIG.
Cement, which is a raw material, is charged from the input port 14 at the upper part of the high-speed air flow agitator 10 with the on-off valve 18 open. After loading, the on-off valve 18 is closed.
The charged cement enters the circulation circuit 13 through an opening provided in the middle of the circulation circuit 13, and then enters the collision chamber 17, which is a space for accommodating an object to be processed, from the outlet 13b of the circulation circuit 13. ..
After the raw material is charged, the rotor (rotating body) 11 arranged inside the stator 16 which is a fixed body is rotated at high speed, so that a high-speed air flow is generated by the rotor 11 and the blade 12 fixed to the rotor 11. The cement in the collision chamber 17 is agitated. During stirring, the particles constituting the cement enter the circulation circuit 13 from the inlet 13a of the circulation circuit 13 provided in the collision chamber 17, and enter the circulation circuit 13 and exit the circulation circuit 13 provided in the central portion of the collision chamber 17. It circulates by being thrown into the collision chamber 17 again from 13b.
In FIG. 3, the arrow indicated by the dotted line indicates the flow of particles (including particles constituting cement and coarse particles and fine particles generated by polishing treatment).

By stirring, the particles constituting the cement collide with the inner wall surface of the collision chamber 17, the rotor 11 and the blade 12, and the particles constituting the cement collide with each other, so that the particles constituting the cement are polished. Coarse particles (particles having a particle size of 20 μm or more) and fine particles (particles having a particle size of less than 20 μm) are generated in which the angular portion of the particle surface is changed to a rounded shape.

The rotation speed of the rotor 11 is preferably 3,000 to 4,200 rpm, more preferably 3,500 to 4,000 rpm. When the rotation speed is 3,000 rpm or more, the fluidity of the cement composition is improved. When the rotation speed exceeds 4,200 rpm, the effect of improving the fluidity of the cement composition reaches a plateau. Further, due to the performance of the high-speed airflow agitator, it is difficult for the rotation speed to exceed 4,200 rpm.
The polishing treatment time is preferably 10 to 60 minutes, more preferably 20 to 50 minutes, still more preferably 20 to 40 minutes, and particularly preferably 20 to 30 minutes. If the time is 10 minutes or more, the fluidity of the cement composition is improved. When the time exceeds 60 minutes, the effect of improving the fluidity of the cement composition reaches a plateau.
The obtained polished product (mixture of coarse particles and fine particles) is discharged from the discharge port 15 by opening the discharge valve 19.

The BET specific surface area of silica fume is 15 to 25 m ² / g, preferably 17 to 23 m ² / g, and particularly preferably 18 to 22 m ² / g. When the specific surface area is ^{less than 15 m 2} / g, the compressive strength of the hardened cementum is reduced. When the specific surface area ^{exceeds 25 m 2} / g, the fluidity of the cement composition decreases.

Examples of the inorganic powder having a 50% volume cumulative particle size of 0.8 to 5 μm (hereinafter, may be abbreviated as “inorganic powder”) include quartz powder (silica powder), volcanic ash, and fly ash (classification or pulverization). , Slag powder, limestone powder, talus powder, mulite powder, alumina powder, silica sol, carbide powder, nitride powder and the like.
One of these may be used alone, or two or more thereof may be used in combination.
Above all, it is preferable to use quartz powder or fly ash from the viewpoint of improving the fluidity of the cement composition and increasing the compressive strength of the hardened cementum.
In the present specification, it is assumed that the inorganic powder having a 50% cumulative particle size of 0.8 to 5 μm does not contain cement.

The 50% volume cumulative particle size of the inorganic powder is 0.8 to 5 μm, preferably 1 to 4 μm, more preferably 1.1 to 3.5 μm, and particularly preferably 1.2 μm or more and less than 3 μm. If the particle size is less than 0.8 μm, the fluidity of the cement composition decreases. When the particle size exceeds 5 μm, the compressive strength of the hardened cementum is reduced.
The 50% volume cumulative particle size of the inorganic powder can be determined using a commercially available particle size distribution measuring device (for example, manufactured by Nikkiso Co., Ltd., product name "Microtrack HRA Model 9320-X100").
Specifically, a cumulative particle size curve can be created using a particle size distribution measuring device, and a 50% volume cumulative particle size can be obtained from the cumulative particle size curve. ^{At this time, 0.06 g of the sample was added to 20 cm 3 of} ethanol, which is a solvent for dispersing the sample, and an ultrasonic disperser (for example, manufactured by Nissei Tokyo Office, product name "US300") was used for 90 seconds. Measure the ultrasonic dispersion.

The maximum particle size of the inorganic powder is preferably 15 μm or less, more preferably 14 μm or less, and particularly preferably 13 μm or less, from the viewpoint of increasing the compressive strength of the hardened cementum.
The 95% volume cumulative particle size of the inorganic powder is preferably 8 μm or less, more preferably 7 μm or less, and particularly preferably 6 μm or less, from the viewpoint of increasing the compressive strength of the cementum cured product.

As the inorganic powder, _{one containing SiO 2} as a main component (for example, quartz powder) is preferable. _{When the content of SiO 2} in the inorganic powder is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more, the compressive strength of the cementum cured product is higher.

In the cement composition, the ratio of cement to 100% by volume of the total amount of cement, silica fume and inorganic powder is 55 to 65% by volume, preferably 57 to 63% by volume. If the ratio is less than 55% by volume, the compressive strength of the hardened cementum is reduced. When the ratio exceeds 65% by volume, the fluidity of the cement composition decreases.
The ratio of silica fume to 100% by volume of the total amount of cement, silica fume and inorganic powder is 5 to 25% by volume, preferably 7 to 23% by volume. If the ratio is less than 5% by volume, the compressive strength of the hardened cementum is reduced. When the ratio exceeds 25% by volume, the fluidity of the cement composition decreases.
The ratio of the inorganic powder to 100% by volume of the total amount of cement, silica fume and the inorganic powder is 15 to 35% by volume, preferably 17 to 33% by volume. If the ratio is less than 15% by volume, the compressive strength of the hardened cementum is reduced. When the ratio exceeds 35% by volume, the fluidity of the cement composition decreases.

The aggregate A includes river sand, land sand, sea sand, crushed sand, silica sand, natural emery sand, artificial fine aggregate (for example, slag fine aggregate, fly ash, etc.) fired fine aggregate, artificial (artificial). ) Emery sand, coarsely pulverized alumina or carbide (for example, silicon carbide, boron carbide, etc.), recycled fine aggregate, or a mixture thereof.
The maximum particle size of the aggregate A is 1.2 mm or less, preferably 1.1 mm or less, and particularly preferably 1.0 mm or less. When the maximum particle size is 1.2 mm or less, the compressive strength of the hardened cementum is high.
Regarding the particle size distribution of the aggregate A, from the viewpoint of improving the fluidity of the cement composition and increasing the compressive strength of the hardened cement material, the proportion of the aggregate having a particle size of 0.6 mm or less is 95% by mass or more. It is preferable that the proportion of aggregate having a particle size of 0.3 mm or less is 40 to 50% by mass, and the proportion of aggregate having a particle size of 0.15 mm or less is 6% by mass or less.
The proportion of aggregate A in the cement composition is preferably 20-40% by volume, more preferably 22-38% by volume, even more preferably 30-37% by volume, and particularly preferably 32-36% by volume. When the ratio is 20% by volume or more, the calorific value of the cement composition becomes small and the shrinkage amount of the cementum cured product becomes small. When the ratio is 40% by volume or less, the compressive strength of the hardened cementum is higher.

As the high-performance water-reducing agent, a high-performance water-reducing agent such as naphthalene sulfonic acid-based, melamine-based, or polycarboxylic acid-based can be used. Above all, a polycarboxylic acid-based high-performance water reducing agent is preferable from the viewpoint of improving the fluidity of the cement composition and increasing the compressive strength of the hardened cementum.
The blending amount of the high-performance water reducing agent is preferably 0.2 to 1.5 parts by mass, more preferably 0.4 in terms of solid content, with respect to 100 parts by mass of the total amount of cement, silica fume and inorganic powder. ~ 1.2 parts by mass. When the amount is 0.2 parts by mass or more, the water reduction performance is improved and the fluidity of the cement composition is improved. When the amount is 1.5 parts by mass or less, the compressive strength of the hardened cementum becomes higher.

As the defoaming agent, a commercially available product can be used.
The amount of the defoaming agent to be blended is preferably 0.001 to 0.1 parts by mass, more preferably 0.01 to 0.07 parts by mass, particularly based on 100 parts by mass of the total amount of cement, silica fume and inorganic powder. It is preferably 0.01 to 0.05 parts by mass. When the amount is 0.001 part by mass or more, the strength development of the cement composition is improved. When the amount exceeds 0.1 parts by mass, the effect of improving the strength development of the cement composition reaches a plateau.

The cement composition contains metal fibers and organic fibers from the viewpoint of improving the bending strength, breaking energy, etc. of the hardened cementum to enhance the impact resistance of the explosion-proof panel and the fire resistance of the explosion-proof panel. ..
The total blending ratio of the fibers (metal fibers, organic fibers, and carbon fibers described later to be blended as needed) in the cement composition is preferably 0.4 to 4% by volume, more preferably 0.6. It is ~ 3.5% by volume, more preferably 0.8 to 3.0% by volume, and particularly preferably 1.0 to 2.7% by volume. When the ratio is 0.4% by volume or more, the bending strength, breaking energy, fire resistance and the like of the cementum hardened body can be improved. When the ratio is 4% by volume or less, the bending strength, fracture energy, fire resistance, etc. of the hardened cementum can be improved without lowering the fluidity and workability of the cement composition.

Examples of the metal fiber include steel fiber, stainless steel fiber, amorphous fiber and the like. Among them, steel fiber is excellent in strength, and is suitable from the viewpoint of cost and availability.
The dimensions of the metal fibers are 0.01 to 1.0 mm in diameter and 0.01 to 1.0 mm in length from the viewpoint of preventing material separation of the metal fibers in the cement composition and improving the bending strength and impact resistance of the hardened cement material. It is preferably 2 to 30 mm, more preferably 0.05 to 0.5 mm in diameter and 5 to 25 mm in length. The aspect ratio (fiber length / fiber diameter) of the metal fiber is preferably 20 to 200, more preferably 40 to 150.

The blending ratio of the metal fiber is preferably 0.3 to 3% by volume, more preferably 0.5 to 2.5% by volume, and particularly preferably 0.7 to 2.3% by volume in the cement composition. When the ratio is 0.3% by volume or more, the bending strength and impact resistance of the hardened cementum are improved. When the ratio is 3% by volume or less, the bending strength and impact resistance of the hardened cementum can be improved without lowering the fluidity and workability of the cement composition.
The shape of the metal fiber is preferably a shape that imparts some physical adhesive force (for example, a spiral shape or a corrugated shape) rather than a linear shape. If the shape is spiral or the like, the metal fiber and the matrix secure the stress while pulling out, so that the bending strength of the hardened cementum is improved.

Examples of the organic fiber include aramid fiber, polyparaphenylene benzobisoxazole fiber, polyethylene fiber, polyarite fiber, polypropylene fiber, polyvinyl alcohol fiber and the like. Of these, polypropylene fiber is preferable from the viewpoint of easy availability and improvement of fire resistance of the hardened cementum.
The dimensions of the organic fibers are 0.005 to 1.000 mm in diameter and 2 to 30 mm in length from the viewpoint of preventing material separation of the organic fibers in the cement composition and improving the fire resistance of the hardened cement material. It is more preferably 0.008 to 0.500 mm in diameter and 3 to 25 mm in length, and further preferably 0.010 to 0.030 mm in diameter and 4 to 10 mm in length. It is particularly preferable that the diameter is 0.012 to 0.020 mm and the length is 4 to 8 mm.
The aspect ratio (fiber length / fiber diameter) of the organic fiber is preferably 20 to 500, more preferably 30 to 490, still more preferably 200 to 480, still more preferably 230 to 470, and particularly preferably 300 to 450. be.
Among them, polypropylene fibers having a diameter of 0.010 to 0.030 mm, a length of 4 to 10 mm, and an aspect ratio (fiber length / fiber diameter) of 230 to 480 are used from the viewpoint of further improving the fire resistance of the hardened cement material. Preferably, polypropylene fibers having a diameter of 0.010 to 0.020 mm, a length of 4 to 8 mm and an aspect ratio (fiber length / fiber diameter) of 300 to 470 are more preferred, having a diameter of 0.012 to 0.020 mm and a length. Polypropylene fibers having a diameter of 4 to 8 mm and an aspect ratio (fiber length / fiber diameter) of 300 to 450 are more preferable.
The proportion of organic fibers in the cement composition is preferably 0.05 to 1.0% by volume, more preferably 0.07 to 0.9% by volume, even more preferably 0.08 to 0.8% by volume, further. It is preferably 0.10 to 0.5% by volume, and particularly preferably 0.15 to 0.3% by volume. When the ratio is 0.05% by volume or more, the fire resistance of the hardened cementum is further improved. When the ratio is 1.0% by volume or less, the compressive strength of the hardened cementum is higher.

The cement composition of the present invention may contain carbon fibers. The proportion of the fibers in the cement composition is preferably 3% by volume or less, more preferably 0.1 to 2.5% by volume, and particularly preferably 0.2 to 2.3% by volume.
Examples of carbon fibers include PAN-based carbon fibers and pitch-based carbon fibers.
The dimensions of the carbon fibers are preferably 0.005 to 1.0 mm in diameter and 2 to 30 mm in length, and 0.01 to 0.01 to 30 mm in diameter, from the viewpoint of preventing material separation of carbon fibers in the cement composition. More preferably, it is 0.5 mm and has a length of 5 to 25 mm. The aspect ratio (fiber length / fiber diameter) of the carbon fibers is preferably 20 to 200, more preferably 30 to 150.

As water, tap water or the like can be used.
The blending amount of water is preferably 10 to 20 parts by mass, more preferably 11 to 18 parts by mass, and particularly preferably 14 to 16 parts by mass with respect to 100 parts by mass of the total amount of cement, silica fume and inorganic powder. When the amount is 10 parts by mass or more, the fluidity of the cement composition is improved. When the amount is 20 parts by mass or less, the compressive strength of the hardened cementum is higher.

The flow value of the mortar composed of the above cement composition (which does not contain aggregate B described later) before curing is 15 times in the method described in "JIS R 5201 (Physical test method for cement) 11. Flow test". The value measured without the falling motion (hereinafter, also referred to as “0 stroke flow value”) is preferably 180 mm or more, more preferably 190 mm or more, and particularly preferably 200 mm or more.
When the flow value is 180 mm or more, workability in manufacturing an explosion-proof panel can be improved.
Further, the compressive strength of the hardened cement material obtained by curing a mortar composed of the above cement composition (which does not contain aggregate B described later) is preferably 300 N / mm ² or more, more preferably 320 N / mm ² or more. , more preferably 330N / mm ² or more, more preferably 350 N / mm ² or more, more preferably 370N / mm ² or more, and particularly preferably 400 N / mm ² or more.

The aggregate A has a modified Mohs hardness of 9 or more (preferably 10 to 14, particularly preferably 11 to 13) (for example, a coarsely pulverized natural or artificial (artificial) emery sand, alumina or carbide). According to a mortar made of a cement composition using (etc.) (which does not contain aggregate B, which will be described later), the compressive strength of the hardened cementum can be 400 N / mm ² or more. In particular, according to natural or artificial (artificial) emery sand, the compressive strength of the hardened cementum can be 430 N / mm ² or more.

The cement composition of the present invention can contain an aggregate B having a maximum particle size of more than 1.2 mm and 13 mm or less.
The aggregate B includes river sand, mountain sand, land sand, sea sand, crushed sand, silica sand, natural emery sand, artificial fine aggregate (for example, slag fine aggregate, fly ash, etc.). , Artificial (artificial) emery sand), recycled fine aggregate, river gravel, mountain gravel, land gravel, crushed stone, artificial coarse aggregate (for example, slag coarse aggregate, fly ash, etc. ), Recycled coarse aggregate, coarsely pulverized alumina or carbide (for example, silicon carbide, boron carbide, etc.), or a mixture thereof.
The maximum particle size of the aggregate B is 13 mm or less, preferably 12 mm or less, more preferably 11 mm or less, and particularly preferably 10 mm or less. When the maximum particle size is 13 mm or less, the strength development of the cement composition is improved, and for example, ^{a compressive strength of 270 N / mm 2} or more can be exhibited.

The maximum particle size of the aggregate B is a value exceeding 1.2 mm from the viewpoint of cost reduction and the like, preferably 3 mm or more, more preferably 5 mm or more, and particularly preferably 7 mm or more.
In the present specification, the "maximum particle size" when the maximum particle size of the aggregate B is 5 mm or more is the nominal size of the sieve having the smallest size among the sieves through which 90% by mass or more of the entire aggregate B passes. Refers to the particle size of the aggregate B indicated by (generally known as the definition of the maximum particle size of the coarse aggregate).

The minimum particle size of the aggregate B is preferably a value exceeding the maximum particle size of the aggregate A, more preferably 2 mm or more, further preferably 3 mm or more, still more preferably 4 mm or more, and particularly preferably 5 mm or more (in this case). , Corresponds to coarse aggregate.)
In the present specification, the minimum particle size of the aggregate B is the entire aggregate B when the particle size of the aggregate B is accumulated from the smallest particle size to the larger particle size. It refers to the particle size of the aggregate B when it reaches 15% by mass.

In the present invention, the ratio of the total amount of the aggregate A and the aggregate B in the cement composition is preferably 25 to 40% by volume, more preferably 28 to 38% by volume, and particularly preferably 30 to 36% by volume. .. When the ratio is 25% by volume or more, the calorific value of the cement composition becomes small and the shrinkage amount of the cementum cured product becomes small. When the ratio is 40% by volume or less, the strength development of the cement composition can be improved.
The ratio of the aggregate B to the total amount of the aggregate A and the aggregate B is preferably 40% by volume or less, more preferably 30% by volume or less, and particularly preferably 25% by volume or less. When the ratio is 40% by volume or less, the strength development (for example, compressive strength) of the cement composition can be improved.
Compressive strength of the aggregate cement composition comprising a B (e.g., concrete) cementitious cured body obtained by curing is preferably 270N / mm ² or more, more preferably 280N / mm ² or more, more preferably 290 N / mm ² or more, more preferably 300N / mm ² or more, more preferably 310N / mm ² or more, more preferably 320N / mm ² or more, and particularly preferably 330N / mm ² or more.

Hereinafter, a method for producing an explosion-proof panel made of a hardened cementum obtained by hardening the above-mentioned cement composition will be described in detail.
An example of the method for producing an explosion-proof panel of the present invention is a molding step of casting a cement composition into a mold to obtain an uncured molded product, and uncured molded product at 10 to 40 ° C. 24. A normal temperature curing step of obtaining a cured molded product by removing the mold from the mold after sealing or aerial curing for an hour or longer, and steam curing or steam curing of the cured molded product at 70 ° C. or higher and lower than 100 ° C. for 6 hours or longer. A heat curing step of obtaining a cured product after heat curing by performing one or both of hot water curing and autoclave curing at 100 to 200 ° C. for 1 hour or more, and a cured product after heat curing at 150 to 200 ° C. It includes a high-temperature heating step of heating for 24 hours or more (excluding heating by autoclave curing) to obtain an explosion-proof panel made of a hardened cement material.

[Molding process]
This step is a step of casting the cement composition into the mold to obtain an uncured molded product.
The method of kneading the cement composition before casting is not particularly limited. Further, the apparatus used for kneading is not particularly limited, and a conventional mixer such as an omni mixer, a pan-type mixer, a biaxial kneading mixer, and a tilting mixer can be used. Further, the casting (molding) method is not particularly limited.
The uncured molded product in this step may consist of a cement composition in which air bubbles in the cement composition are reduced or removed. By reducing or removing air bubbles in the cement composition, the strength development of the cement composition can be further improved.
As a method for reducing or removing air bubbles in the cement composition, (1) a method of kneading the cement composition under reduced pressure, and (2) before placing the kneaded cement composition in a mold. Examples thereof include a method of defoaming by reducing the pressure, and (3) a method of placing the cement composition in a mold and then defoaming by reducing the pressure.

[Normal temperature curing process]
In this step, the uncured molded product is sealed or cured in air at 10 to 40 ° C. (preferably 15 to 30 ° C.) for 24 hours or more (preferably 24 to 72 hours, more preferably 24 to 48 hours). This is a step of removing the mold from the mold to obtain a cured molded product.
When the curing temperature is 10 ° C. or higher, the curing time can be shortened. When the curing temperature is 40 ° C. or lower, the compressive strength of the cementum cured product (explosion-proof panel) can be further increased.
If the curing time is 24 hours or more, defects such as chips and cracks are less likely to occur in the cured molded product during demolding.
Further, in this step, when the cured molded product ^{exhibits a compressive strength of preferably 20 to} 100 N / mm 2, more preferably 30 to 80 N / mm ² , the cured molded product is removed from the mold. Is preferable. When the compressive strength is 20 N / mm ² or more, defects such as chips and cracks are less likely to occur in the cured molded product during demolding. When the compressive strength is 100 N / mm ² or less, the cured molded product can be made to absorb water with less labor in the water absorption step described later.

[Heat curing process]
In this step, the cured molded product obtained in the previous step is steam-cured or hot-water-cured at 70 ° C. or higher and lower than 100 ° C. (preferably 75-95 ° C., more preferably 80-92 ° C.) for 6 hours or longer. This is a step of performing one or both of autoclave curing at 100 to 200 ° C. (preferably 160 to 190 ° C.) for 1 hour or more to obtain a cured product after heat curing.
When only steam curing or hot water curing is performed in this step, the curing time is preferably 24 hours or more, more preferably 24-96 hours, and particularly preferably 36-72 hours. When only autoclave curing is performed, the curing time is preferably 8 to 60 hours, more preferably 12 to 48 hours. When performing both steam curing or hot water curing and autoclave curing (for example, when performing steam curing or hot water curing and then autoclave curing), the curing time in steam curing or hot water curing is preferably 6 to 72 hours. , More preferably 12 to 48 hours, and the curing time in autoclave curing is preferably 1 to 24 hours, more preferably 4 to 18 hours.
In this step, if the curing temperature is within the above range, the curing time can be shortened and the compressive strength of the cementum cured product can be improved.
Further, in this step, if the curing time is within the above range, the compressive strength of the hardened cementum can be improved.

[High temperature heating process]
In this step, the cured product after heat curing is heated at 150 to 200 ° C. (preferably 170 to 190 ° C.) for 24 hours or more (preferably 24 to 72 hours, more preferably 36 to 48 hours) and heated (however, autoclave). This is a step of obtaining an explosion-proof panel made of a hardened cement material obtained by curing the cement composition by (excluding heating by curing).
The heating in this step is usually performed in a dry atmosphere (in other words, in a state where water or water vapor is not artificially supplied).
When the heating temperature is 150 ° C. or higher, the heating time can be shortened. When the heating temperature is 200 ° C. or lower, the compressive strength of the hardened cementum can be further improved.
When the heating time is 24 hours or more, the compressive strength of the hardened cementum can be further improved.

[Water absorption process]
Between the normal temperature curing step and the heat curing step, a water absorption step of causing the cured molded product obtained in the normal temperature curing step to absorb water may be included.
Examples of the method of allowing the cured molded product to absorb water include a method of immersing the molded product in water. Further, in the method of immersing the molded body in water, from the viewpoint of increasing the amount of water absorption in a short time and increasing the compressive strength of the cementified cured product, (1) the molded body is immersed in water under reduced pressure. (2) A method of immersing the molded body in boiling water and then lowering the water temperature to 40 ° C. or lower while the molded body is immersed, (3) The molded body. A method of immersing the molded product in boiling water, then taking the molded product out of the boiling water, and then immersing the molded product in water at 40 ° C. or lower. (4) The molded product is placed under pressure. A method of immersing the molded body in water or (5) a method of immersing the molded body in an aqueous solution in which a drug for improving the permeability of water into the molded body is dissolved is preferable.

Examples of the method of immersing the molded body in water under reduced pressure include a method of using equipment such as a vacuum pump and a large decompressing container.
Examples of the method of immersing the molded product in boiling water include a method of using equipment such as a high-temperature and high-pressure container and a hot and hot water tank.
The time for immersing the cured molded product in water under reduced pressure or boiling water is preferably 3 minutes or longer, more preferably 8 minutes or longer, and particularly preferably 20 minutes, from the viewpoint of increasing the water absorption rate. That is all. The upper limit of the time is preferably 60 minutes, more preferably 45 minutes from the viewpoint of increasing the compressive strength of the hardened cementum.

The water absorption rate in the water absorption step is determined when the cement composition does not contain coarse aggregate (when the cement composition does not contain aggregate B or when aggregate B in the cement composition does not correspond to coarse aggregate). The ratio of water to 100% by volume of the cured compact of φ50 × 100 mm is preferably 0.2% by volume or more, more preferably 0.3 to 2.0% by volume, and particularly preferably 0.35 to 1.7% by volume. %, And when the cement composition contains coarse aggregate (when aggregate B in the cement composition corresponds to coarse aggregate), the ratio of water to 100% by volume of the cured compact of φ100 × 200 mm is It is preferably 0.2% by volume or more, more preferably 0.3 to 2.0% by volume, and particularly preferably 0.35 to 1.7% by volume.
When these water absorption rates are 0.2% by volume or more, the compressive strength of the hardened cementum can be further increased.

Since the explosion-proof panel of the present invention is made of a hardened cementum having high compressive strength, cracks and the like are unlikely to occur. Further, since the explosion-proof panel of the present invention is made of a hardened cementum having high compressive strength, its thickness can be reduced. As a result, the weight of the explosion-proof panel can be reduced, and the explosion-proof wall and the storage for explosives and the like can be easily constructed.
Further, the explosion-proof panel of the present invention is excellent in fire resistance and impact resistance.
Further, the explosion-proof panel of the present invention is excellent in dimensional stability. For example, a 40 × 40 × 160 mm specimen measured in accordance with “JIS A 1129-2: 2010 (Mortar and concrete length change measurement method-Part 2: Contact gauge method)” is stored for 6 months. The shrinkage strain of the hardened cementum (explosion-proof panel of the present invention) is preferably 10 × ^10-6 or less, more preferably 8 × ^10-6 or less, and particularly preferably 6 × ^10-6 or less. be.
Further, the explosion-proof panel of the present invention has a large bending strength. The bending strength of the cemented hardened material (explosion-proof panel of the present invention) measured in accordance with "JSCE-G 552-2010 (Bending strength and bending toughness test method of steel fiber reinforced concrete)" is preferable. the 30 N / mm ² or more, more preferably 32N / mm ² or more, more preferably 35N / mm ² or more, and particularly preferably 37N / mm ² or more.

The shape of the explosion-proof panel of the present invention may be appropriately determined according to the shape of the structure constructed using the panel, but from the viewpoint of versatility, it is rectangular like the explosion-proof panel 1 shown in FIG. It may be in the shape of a (square or rectangular) plate.
From the viewpoint of strength and impact resistance, the thickness of the explosion-proof panel is preferably 6 cm or more, more preferably 8 cm or more, and particularly preferably 10 cm or more. From the viewpoint, it is preferably 30 cm or less, more preferably 25 cm or less, still more preferably 20 cm or less.
The vertical and horizontal dimensions of the explosion-proof panel are preferably 3 m or less, more preferably 2.5 m or less, and particularly preferably 2 m or less from the viewpoint of ease of handling, and from the viewpoint of work efficiency. It is preferably 1 m or more, more preferably 1.5 m or more, and particularly preferably 2 m or more.

Examples of the concrete structure constructed by using the explosion-proof panel of the present invention include an explosion-proof wall formed by connecting the explosion-proof panels vertically and horizontally. When it is desired to increase the thickness of the explosion-proof wall (for example, 30 cm or more), a plurality of explosion-proof panels may be stacked and constructed.
In addition, in order to construct a storage (storage facility) for substances with a risk of explosion such as explosives, the explosion-proof panel of the present invention shall be used as a member of the wall and roof (floor if necessary) of the storage. Can be done.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.
[Material used]
The materials used are as shown below.
(1) Cement: Low-grade Portland cement (manufactured by Taiheiyo Cement)
(2) Silica fume A: BET specific surface area 20 m ² / g
(3) Silica fume B: BET specific surface area 17 m ² / g
(4) Inorganic powder A: Silica stone powder, 50% cumulative particle size 2 μm, maximum particle size 12 μm, 95% cumulative particle size 5.8 μm
(5) Inorganic powder B: silica stone powder, 50% cumulative particle size 7 μm, maximum particle size 67 μm, 95% cumulative particle size 27 μm
(6) Aggregate A (fine aggregate): Silica sand (maximum particle size 1.0 mm, particle size of 0.6 mm or less: 98% by mass, particle size of 0.3 mm or less: 45% by mass, 0 .15 mm or less particle size: 3% by mass)
(7) Polycarboxylic acid-based high-performance water reducing agent: Solid content 27.4% by mass, manufactured by Floric, trade name "Floric SF500U"
(8) Defoamer: Made by BASF Japan, trade name "Master Air 404"
(9) Water: Tap water (10) Metal fiber: Steel fiber (diameter: 0.2 mm, length: 15 mm)
(11) Organic fiber A: Polypropylene fiber (diameter: 0.025 mm, length: 6 mm, aspect ratio: 240)
(12) Organic fiber B: Polypropylene fiber (diameter: 0.014 mm, length: 6 mm, aspect ratio: 429)
(13) Organic fiber C: Polypropylene fiber (diameter: 0.018 mm, length: 6 mm, aspect ratio: 333)
(14) Aggregate B (coarse aggregate): Hard sandstone crushed stone 1005 (grain size: 5 to 10 mm)

[Example 1]
Cement, silica fume A and inorganic powder A were mixed so that each ratio of cement and the like was as shown in Table 1 in 100% by volume of the total amount of the powder raw materials (cement, silica fume A and inorganic powder A). The obtained mixture and the amount of the aggregate A in which the ratio of the aggregate A in the cement composition was the ratio shown in Table 1 were put into an omnimixer and kneaded for 15 seconds.
Next, water, a polycarboxylic acid-based high-performance water reducing agent, and a defoaming agent were added to the omnimixer in the amounts shown in Table 1 and kneaded for 2 minutes.
After kneading, the kneaded material adhering to the side wall in the omnimixer was scraped off, and kneading was further carried out for 4 minutes.
Then, the amount of the fiber whose ratio of the metal fiber and the organic fiber in the cement composition became the ratio shown in Table 1 was put into the omnimixer, and kneaded for another 2 minutes.
The flow value of the cement composition after kneading was measured in the method described in "JIS R 5201 (Physical test method for cement) 11. Flow test" without performing 15 falling motions. In addition, in this specification, the flow value is referred to as "0 stroke flow value".

The obtained kneaded product was cast into a cylindrical mold having a diameter of 50 × 100 mm to obtain an uncured molded product. After casting, the uncured molded product was sealed and cured at 20 ° C. for 48 hours, and then demolded to obtain a cured molded product. The compression strength at the time of demolding was 45 N / mm ² .
This molded product was immersed in water for 30 minutes in a depressurized desiccator (indicated as "under reduced pressure" in Table 2). The depressurization was performed using an "Aspirator (AS-01)" manufactured by AS ONE. The mass of the molded product before and after immersion was measured, and the water absorption rate was calculated from the obtained measured values.
After the immersion, the molded product was steam-cured at 90 ° C. for 48 hours, then lowered to 20 ° C., and then heated at 180 ° C. for 48 hours.
The compressive strength of the molded product (hardened cementum) after heating was measured according to "JIS A 1108 (concrete compressive strength test method)".
Moreover, the bending strength of the obtained hardened cement material was measured according to "JSCE Standard JSCE-G 552-2010 (Bending strength and bending toughness test method of steel fiber reinforced concrete)".

Further, the heated molded body (cementized hardened body) was heated using a refractory furnace, and the fire resistance when heated for 60 minutes and the fire resistance when heated for 180 minutes were evaluated. The heating was performed for a predetermined time (60 minutes or 180 minutes) according to the heating curve defined in "ISO834", and after heating, it was naturally cooled. The maximum temperature in the above heating was 900 ° C. when heated for 60 minutes and 1,100 ° C. when heated for 180 minutes.
The fire resistance of the cooled molded product (cementum-hardened product) was evaluated using the presence or absence of explosion, the mass reduction rate, and the residual compressive strength, with particular emphasis on the presence or absence of explosion. The smaller the explosion, the smaller the mass reduction rate, and the larger the residual compressive strength, the better the fire resistance.

Further, a flat plate specimen having a length of 550 mm, a width of 100 mm, and a thickness of 25 mm was produced in the same manner as the molded product (cementum cured product) after heating.
As shown in FIG. 2, a steel weight 3 (mass 20 kg, tip diameter 200 mm) is placed in the center of the flat plate specimen 2, the first time is 10 cm, the second time is 20 cm, the third time is 30 cm, and so on. By increasing the drop height by 10 cm and free-falling each time (for example, the fifth free-fall is performed from a height of 50 cm), repeated loading is applied, and the flat plate specimen is dropped at any number of times. The number of times that 2 broke was measured.
The impact resistance of the hardened cementum was evaluated using the obtained number of times. The greater the number of times, the better the impact resistance.
Table 2 shows the evaluation (number of times) of 0-strike flow value, water absorption rate, compressive strength, bending strength, fire resistance and impact resistance. In Table 2, "◎" indicates that the fire resistance is extremely excellent (the crack width of the molded product after cooling is less than 1 mm), and "○" is excellent in fire resistance (after cooling). The crack width of the molded product is 1 mm or more and less than 10 mm), and "x" indicates that the fire resistance is inferior (the crack width of the molded product after cooling is 10 mm or more and there is peeling). ..
Table 2 also shows the 0-stroke flow values and the like in Examples and Comparative Examples described later.

[Example 2]
A cement composition and a hardened cementum (molded body after heating) were obtained in the same manner as in Example 1 except that the blending amount of the metal fiber was changed to 1.0% by volume.
In the same manner as in Example 1, the zero-strike flow value of the cement composition was measured. The compression strength at the time of demolding was 45 N / mm ² .

[Example 3]
Except for changing the blending amount of water per 100 parts by mass of the powder raw material from 15 parts by mass to 13 parts by mass and changing the blending amount of the high-performance water reducing agent from 0.79 parts by mass to 0.82 parts by mass. Obtained a cement composition and a hardened cementum (molded body after heating) in the same manner as in Example 1.
In the same manner as in Example 1, the zero-strike flow value of the cement composition was measured. The compression strength at the time of demolding was 50 N / mm ² .

[Example 4]
The compounding ratio of silica fume A was changed from 10% by volume to 20% by volume, the compounding ratio of inorganic powder A was changed from 30% by volume to 20% by volume, and the molded product after demolding was placed in a desiccator under reduced pressure. The cement composition and the hardened cement material (heated) were obtained in the same manner as in Example 1 except that the mixture was immersed in boiling water for 30 minutes instead of being immersed in water (indicated as "boiling water" in Table 2). Later molded body) was obtained.
In the same manner as in Example 1, the 0-stroke flow value and the like were measured.

[Example 5]
The blending amount of water per 100 parts by mass of the powder raw material was changed from 15 parts by mass to 11 parts by mass, and the blending amount of aggregate A was changed from 35.5% by volume to 30.0% by mass, resulting in high-performance water reduction. The blending amount of the agent was changed from 0.79 parts by mass to 0.86 parts by mass, and the molded product after demolding was immersed in boiling water for 30 minutes instead of being immersed in water in a depressurized desiccator. A cement composition and a cementified hardened product (molded product after heating) were obtained in the same manner as in Example 1 except for the above.
In the same manner as in Example 1, the 0-stroke flow value was measured and the like. The compression strength at the time of demolding was 54 N / mm ² .

[Example 6]
Except for changing the blending amount of aggregate A from 35.5% by volume to 28.5% by volume and using an amount of aggregate B in which the proportion of aggregate B in the cement composition is 7.0% by volume. Made a cement composition in the same manner as the cement composition of Example 4.
In the production of the cement composition, each material (powder raw material, aggregate A, water, polycarboxylic acid-based high-performance water reducing agent, metal fiber, organic fiber and defoaming agent) was kneaded in the same manner as in Example 1. After that, the aggregate B was further added to the omnimixer and kneaded for 1 minute.
A cementum hardened product was obtained in the same manner as in Example 4 except that the obtained cement composition (kneaded product) was cast into a cylindrical mold having a diameter of 100 × 200 mm.
The water absorption rate was calculated in the same manner as in Example 1. The compression strength at the time of demolding was 37 N / mm ² .

[Example 7]
Organic fiber B is used instead of organic fiber A, the ratio of organic fiber B in the cement composition is 0.1% by volume, and the amount of the high-performance water reducing agent compounded per 100 parts by mass of the powder raw material (solid). A cement composition and a hardened cementaceous product (molded product after heating) were obtained in the same manner as in Example 1 except that the fractional conversion) was 0.83 parts by mass.
In the same manner as in Example 1, the zero-strike flow value of the cement composition was measured, the water absorption rate of the hardened cementum was calculated, the compressive strength was measured, and the fire resistance when heated for 180 minutes was evaluated. The compression strength at the time of demolding was 48 N / mm ² .

[Example 8]
A cement composition and a hardened cementum (molded body after heating) were obtained in the same manner as in Example 7 except that the proportion of the organic fiber B in the cement composition was 0.2% by volume.
In the same manner as in Example 7, the zero-strike flow value of the cement composition was measured. The compression strength at the time of demolding was 47 N / mm ² .
[Example 9]
The cement composition and the hardened cementum were obtained in the same manner as in Example 7 except that the organic fiber C was used instead of the organic fiber B and the ratio of the organic fiber C in the cement composition was 0.2% by volume. (Molded body after heating) was obtained.
In the same manner as in Example 7, the zero-strike flow value of the cement composition was measured. The compression strength at the time of demolding was 47 N / mm ² .

[Comparative Example 1]
Cement, silica fume B and inorganic powder B were mixed so that each ratio of cement and the like was as shown in Table 1 in 100% by volume of the total amount of the powder raw materials (cement, silica fume B and inorganic powder B). The obtained mixture and a fine aggregate having an amount such that the ratio of the aggregate A in the cement composition was as shown in Table 1 were put into an omnimixer and kneaded for 15 seconds.
Next, water, a polycarboxylic acid-based high-performance water reducing agent, and a defoaming agent were added to the omnimixer in the amounts shown in Table 1 and kneaded for 2 minutes.
After kneading, the kneaded material adhering to the side wall in the omnimixer was scraped off, and kneading was further carried out for 4 minutes.
Using the obtained kneaded product as a material, a cementum hardened product was obtained in the same manner as in Example 1.
Various physical properties of the obtained kneaded product (cement composition) and its cured product were measured in the same manner as in Example 1.

From Table 2, it can be seen that the zero-strike flow value is 220 mm or more according to the cement compositions (Examples 1 to 5, 7 to 9) used for the explosion-proof panel of the present invention.
Further, cementitious cured body obtained by curing the cementitious composition (Example 1-9) is a compressive strength of 338N / mm ² or more and is the bending strength of 34N / mm ² or more, the mechanical strength It can be seen that (compression strength, bending strength) is very large.
Further, the hardened cementum is excellent in fire resistance and impact resistance. Among them, the cementitious cured product (Examples 7 to 9) having an organic fiber diameter of 0.018 mm or less has a small proportion of organic fibers (0.1 to 0.2% by volume), but is described in Examples. Excellent fire resistance (heating time: 180 minutes) and impact resistance equal to or higher than the cemented hardened material (organic fiber diameter: 0.025 mm, organic fiber ratio: 0.5% by volume) in 1. You can see that. In particular, it can be seen that the cementum cured products (ratio of organic fibers: 0.2% by volume) in Examples 8 to 9 are extremely excellent in fire resistance (heating time: 180 minutes).
On the other hand, in Comparative Example 1, the compressive strength of the hardened cementum was 290 N / mm ^2, which is smaller than that of Examples 1 to 6. Further, in Comparative Example 1, it can be seen that the fire resistance and the impact resistance are inferior.

1 Explosion-proof panel 2 Flat plate specimen 3 Steel weight 10 High-speed airflow agitator 11 Rotor 12 Blade 13 Circulation circuit 13a Circulation circuit inlet 13b Circulation circuit outlet 14 Input port 15 Discharge port 16 stator 17 Collision chamber 18 On-off valve 19 Discharge valve

Claims (7)

Explosion-proof panel made of hardened cementum
The hardened cement material is cement, silica fume with a BET specific surface area of 15 to 25 m ² / g, an inorganic powder with a 50% volume cumulative particle size of 0.8 to 5 μm, and an aggregate A having a maximum particle size of 1.2 mm or less. , High-performance water reducing agent, defoaming agent, metal fiber, organic fiber and water, and the ratio of the cement to 100% by volume of the total amount of the cement, the silica fume and the inorganic powder is 55 to 65% by volume. the proportion of silica fume is 5 to 25 vol%, Ri cured body der proportion of the inorganic powder cement composition from 15 to 35% by volume,
The metal fiber is a steel fiber having a diameter of 0.05 to 0.5 mm, a length of 5 to 25 mm, and an aspect ratio (fiber length / fiber diameter) of 40 to 150.
The organic fiber is a polypropylene fiber having a diameter of 0.012 to 0.018 mm, a length of 4 to 8 mm, and an aspect ratio (fiber length / fiber diameter) of 333 to 450.
An explosion-proof panel characterized in that the proportion of the metal fibers in the cement composition is 0.7 to 2.3% by volume and the proportion of the organic fibers is 0.15 to 0.3% by volume. The above-mentioned cement includes coarse particles having a particle size of 20 μm or more, which is obtained by polishing particles constituting moderate-heat Portorand cement or low-heat Portorand cement, and deforming an angular surface portion into a rounded shape, and the above-mentioned polishing. The explosion-proof according to claim 1, which contains fine particles having a particle size of less than 20 μm produced by the treatment, has a 50% volume cumulative particle size of 10 to 18 μm, and has a brain specific surface area of 2,100 to 2,900 cm ^{2 / g.} Panel for. The cement composition does not contain an aggregate having a maximum particle size of more than 1.2 mm, and the cement composition does not contain an aggregate.
The explosion-proof panel according to claim 1 or 2 , wherein the hardened cementum has a compressive strength of 300 N / mm ^{2 or more.} The explosion-proof panel according to claim 1 or 2 , wherein the cement composition contains an aggregate B having a maximum particle size of more than 1.2 mm and 13 mm or less. The explosion-proof panel according to claim 4 , wherein the hardened cementum has a compressive strength of 270 N / mm ² or more. The method for manufacturing an explosion-proof panel according to any one of claims 1 to 5.
A molding step of casting the above cement composition into a mold to obtain an uncured molded product, and
The uncured molded body is sealed or cured in the air at 10 to 40 ° C. for 24 hours or more, and then removed from the mold to obtain a cured molded body at room temperature.
The cured molded product is cured by steam curing or hot water curing at 70 ° C. or higher and lower than 100 ° C. for 6 hours or longer, or autoclave curing at 100 to 200 ° C. for 1 hour or longer, and then curing after heat curing. The heat curing process to get the body and
A high-temperature heating step of heating the cured product after heat curing at 150 to 200 ° C. for 24 hours or more (excluding heating by autoclave curing) to obtain the explosion-proof panel.
A method for manufacturing an explosion-proof panel, which comprises. The method for manufacturing an explosion-proof panel according to claim 6 , further comprising a water absorption step of causing the cured molded product to absorb water between the normal temperature curing step and the heat curing step.

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